Ribbon feed



J. H. GRUVER Feb. 1, 1966 RIBBON FEED Filed April 25, 1953 4 Sheets-Sheet 1 INVENTOR. JOHN H. GRUVER m 16% ATTORNEY Feb. 1, 1966 J. H. GRUVER 3,232,508

RIBBON FEED Filed April 25, 1963 4 Sheets-Sheet 2 4 L3 2a INVENTOR.

JOHN H. GFPUVER ATTORNEK J. H. GRUVER Feb. 1, 1966 RIBBON FEED 4 Sheets-Sheet 3 Filed April 25, 1963 INVENTOR. JOHN H. Grauvsf? A T TOE-WE K J. H. GRUVER Feb. 1, 1966 RIBBON FEED 4 Sheets-Sheet 4 Irv:

INVENTOR H. GEL/VHF? Jomv ATTORNE K United States Patent 3,232,508 RIBBON FEED John H. Grover, Cleveland, Ohio, assignor to Addressegraph-Multigraph Corporation, Cleveland, Ohio, a corporation of Delaware Filed Apr. 25, 1963, Ser. No. 275,609 11 Claims. (Cl. 226114) This invention relates to ribbon feed ng and especially to feeding of delicate strips or ribbons in intermittent fashion with feed strokes of substantial length.

Ribbon feeding mechanisms for printing machines, especially those designed to print from individual embossed printing devices such as address plates, have heretofore been arranged to employ cloth ribbons, and to feed forward a small ribbon increment each time an impression is taken. In this way the ribbon surface used in printing is very gradually changed and any particular area is used several times before it passes out of the printing zone. It is then given an opportunity to recover by capillary ink redistribution to condition it for its next use on the reverse pass of the ribbon. A feeding mechanism of this sort normally moves the ribbon in short steps of between /8 inch and inch, and moves the ribbon primarily by alternately driving the ribbon spools so that the ribbon is used a number of times before it is reinked or discarded. The length of the ribbon feed step is usually non-uniform due to the spool drive type of feed. The ribbon is usually about 15 yards long and a full spool weighs only about three ounces.

More recent applications for machines of this sort require a quality of impression beyond that which can be achieved with absorbent cloth ribbons, and this has made it necessary to adapt the machines for use with ribbons of the carbon paper type. These ribbons carry a pressure transferable coating on one surface of a rather delicate strip of paper material, and the paper strip usually used for these applications will withstand only between 10 and 15 pounds straight tensile pull before failure. Since these ribbons are often intended for a single use, it is necessary to feed the ribbon in only one direction, but for many applications the ribbon must be fed forward the full length of a printing area, often about three inches, between impressions. Due to the single use feature it is important to use large rolls of ribbon to avoid unacceptably frequent changes. Accordingly, the ribbon, for convenience, may run 2800 yards in length and a full spool of this length would be 10 inches in diameter and would weigh six poimds approximately. In order not to severly impair the speed of the over-all machine operation the long feedin stroke above mentioned must take place quite rapidly with the result that inertia effects such as excessively high tensile stresses in the ribbon with resulting breakage, overtravel of the supply spool, and the like, tend to appear and prevent satisfactory functioning of the equipment.

Moreover, there are important economic factors which must be taken into consideration. Carbon paper ribbon is inherently more costly to use than impregnated cloth ribbon because of its single or limited use properties. In order to prevent the ribbon cost from assuming impractically large proportions it is found necessary to control the ribbon feed much more accurately so that at each ribbon advance just enough ribbon is fed to present a fresh surface, with an absolute minimum of Waste space between impressions. Preferably the arrangement should also include a ready adjustment so that the distance the ribbon moves at each stroke can be set to correspond with printing areas of different maximum lengths to accommodate printing assignments of different sorts on the same machine, while using the ribbon as economically as possile for each assignment.

From the foregoing discussion it can 'be seen that the proper handling of a delicate ribbon of the carbon paper type on a printing machine requiring rapid feed for high output with a heavy ribbon spool and rather long ribbon advancing strokes, and with acceptable ribbon economy presents distinct problems of ribbon feed control not ordinarily encountered. While there are numerous arrangements devised for carefully controlling the advancing of strips, these prove to be either applicable for continuous feed only, or to involve so much in the way of mechanism and consequent expense as to render them commercially impractical for application to the type of ofiice machine here under consideration.

The present invention has for an object, therefore, the intermittent feeding of delicate ribbons on large spools with relatively long strokes at a high feed rate during the feed stroke period without danger of breaking the ribbons.

Another object of the invention is the intermittent feed ing of a delicate ribbon through an accurate uniform distance at each feeding stroke.

A further object of the invention is the provision for adjustability in a ribbon feed mechanism so that the ribboncan be fed in accurate increments whose length will remain constant and accurate once set, and whose length can be: readily changed as desired to meet different work requirements.

Still a further object of the invention is the achieving of each of the foregoing objects or any combination thereof in a manner consistent with the current economic requirements imposed on the manufacture and sale of a printing machine of the ofiice equipment type.

In accordance with the invention the foregoing objects are attained by providing a positively driven feed drum for the ribbon actuated by a cyclically driven portion of the printing machine mechanism and squeezing the ribbon" against the surface of this drum by means of a pressure; roller. The supply spool is braked by a simple friction brake applied to the surface of the ribbon coil on the spool, and the collecting spool is continuously urged in a winding direction by a friction clutch. Between each of the spools and the feed drum is a simple low-inertia vent the formation of slack loops tending to make possible the creation of impact stresses when suddenly pulled taut.

A feature of the invention is the provision of an oscillating ratchet drive for the ribbon feed drum, which makes possible a ready adjustment for the length of the feed, stroke.

A further feature of the invention is the arrangement of the ribbon feed drum and pressure roller in such a Way that any carbon transfer to the drum or roller at the feed. point is minimized, and any carbon material transferred is presented in a position for ready disposal so that buildup of a carbon deposit on either is avoided.

Another object of the invention is the provision of means whereby the threading of the delicate ribbon material may be easily and expeditiously accomplished, when replenishment is required, without danger of ribbon damage.

Other objects, features and advantages will appear hereinafter as the description proceeds.

In the drawing:

FIG. 1 is a fragmentary front elevation of an address printing machine showing the ribbon feed of the invention;

FIG. 2 is a top plan of the ribbon advancing portion of the ribbon feed drawn to a larger scale and with parts in section;

FIG. 2a is a detail section substantially on line 2a2a of FIG. 2;

FIG. 3 is a section on line 3-3 of FIG. 2;

FIG. 4 is a section on line 44 of FIG. 2;

FIG. 5 is a section on line 5-5 of FIG. 1; and

FIG. 6 is a detail elevation to a larger scale with parts broken away illustrating the feed stroke adjustment device.

Referring to the drawing, the printing machine comprises a frame member 11 to which is secured an anvil 13 for supporting a printing device P, such as an embossed sheet metal plate, in printing position. A suitable platen mechanism 15 is supported above the anvil in position to take impressions from the printing device P when required. A ribbon R of the carbon paper type is trained above the printing device with its carbon surface upwardly directed in position to provide a mark on a document inserted between the ribbon R and platen 15 when the latter is operated.

The carbon ribbon R is wound on a supply spool 17 which is mounted for free rotation on a bracket 19 depending from frame 11, and extends across the upper surface of anvil 13, through a ribbon advancing mechanism 21 and thence to a collection spool 23 mounted on a bracket 25 depending from frame 11.

The ribbon advancing mechanism 21 is shown in detail in FIGS. 2, 3, 4 and 6, and comprises an auxiliary frame 27 with spaced bearings 29 and 31 rotatably supporting a feed drum shaft 33. Drivingly connected to the shaft 33 is a feed drum 35 and gear 37. One end of the shaft 33, designated 33a, extends through and beyond its bearing 31, and has pinned thereto a sleeve 39. Slidable on the sleeve 39 but keyed thereto for rotation therewith are brake plates 41. In the form shown these plates have radially inwardly extending tongues 43 which ride in slots 45 in sleeve 39. Interspersed between the plates 41 are friction elements 47 which surround the sleeve 39 and are prevented from rotation therewith by engagement with a pin 49 mounted on frame 27. A compression spring 51 surrounds the sleeve 39 and acts to compact the plates 41 and elements 47 to an extent determined by the setting of a nut 53 threaded on the end of sleeve 39. The parts 39 to 53 just described comprise an adjustable friction brake assembly for shaft 33 which assembly is as a whole designated by reference character 55.

Adjacent and parallel to the feed dlum 35 is a guide pin 57 afiixed to frame 27 and arranged to hold the ribbon R at the proper printing level as it approaches the feed drum. At the other side of the drum 35 are a pair of notches 59 in the frame 27 designed to cradle a pressure roller assembly 61 which comprises a shaft 63, a pressure roller 64 rotatable on the shaft, a gear 65 pinned to. the shaft, two bushings 67 rotatably embracing the shaft and a pinion 69 pinned to one end of the shaft exteriorly of the frame 27. Each of the bushings 67 is mounted in a block 71 received in one of the notches 59 and slightly narrower than the same for limited shifting movement towards and away from the feed drum. Springs 73 arranged in recesses 75 of the frame 27 are designed to urge the pressure roller assembly 61 away from the feed drum 35, only one of these being shown in FIG. 2. It will be understood, of course, that the corresponding spring arrangement on the other side of the frame is identical.

The position of the pressure roller during operation is determined by latch means comprising a pair of swinging arms 77, 77-, one at each side of the frame 27. The arms 77 are each rockable on the eccentric portion 79 of a pivot pin 81 which has a head 83 for adjusting its radial position and which may be clamped in adjusted position by a nut 85 threaded thereon. A notch 87 at the end of a cam surface 88 on each latch arm (see FIG. 2a) is designed to receive and position the corresponding bushing 67 and with it the associated end of shaft 63 when the arm 77 is depressed. When the arm 77 is raised, springs 73 urge the pressure roller assembly 61 away from the feed drum 35 to provide for threading of the ribbon R therebetween. When the arms 77 are both lowered, cam

surfaces 88 direct the bushings 67 into notches 87 which action forces the roller 64, in opposition to springs 73, into contact with the feed drum 35 or the ribbon thereon. The degree of pressure exerted can be adjusted to the de sired value by setting the positions of the eccentric portions 79 of pivot pins 31 in a manner which will be readily understod by reference to the drawing.

The surfaces of the feed drum and pressure roller may be variously composed, but in the preferred arrangement, feed drum 35 has a knurled steel surface, and pressure roller 64 is of a hard but slightly resilient plastic material, e.g. polyurethane, which has a smooth surface and little or no affinity for the carbon ink layer on the ribbon R. The ribbon is used in such a way that the paper surface is in contact with the feed drum and the carbon surface touches the pressure roller The grips thus provided is quite positive and admits of very accurate ribbon feed control with virtually zero slippage at the start of each feed stroke.

In order to insure that the latch means is retained in operative position, there is provided a clamp plate 91 with lateral fingers 93, 93 which overlie the upper ends of latch arms 77. The plate 91 is held firmly in place on the frame 27 in a readily removable fashion by hand screws 95. Integrally associated with plate 91 is a scraper 97 which is disposed in a position to approach the outside surface of pressure roller 64 when plate 91 is fastened in place (see FIG. 3). It will be noted that the connection between plate 91 and the frame 27 admits of some play so that the edge of scraper 97 can be set in accurate relationship to the roller 64 and thereby knock loose any flakes of carbon coating material which may chance to remain on roller 64. A receptacle 99 is releasably held on frame 11 as by screws 101 in a position to catch any carbon material which may be thus removed from roller 64.

When the latch arms 77 are lowered, shaft 63 is held in such position that its gear 65 is meshed with gear 37 on the feed drum shaft 33. In addition, shaft 63 has a socket 103 on its forward end formed interiorly with a suitable driving or clutch configuration. A crank 105 has a mating end 107 which may be placed in the socket and used to rotate shaft 63. This rotates meshing gears 65 and 37 and hence the feed drum 35 and provides a convenient way to feed forward the ribbon R during a threading operation.

A drive mechanism (see especially FIGS. 2 and 6) is provided for intermittently operating the feed drum in time with the machine operation, the prime moving action being taken from a link 109 which oscillates in time with the machine cycle, shifting to the left to position A during platen operation for printing, and then shifting to the right to position B between printing operations when the platen is raised. The link 109 is connected to and swings one end of a drive lever 111, the other end of which is freely pivoted on a stud 113 extending from the frame 27. R0- tatable on the stud 113 adjacent the lever 111 is a rotor comprising a hub 115 with a ratchet wheel 117 and a large gear 119 drivingly associated therewith. The gear 119 is positioned to mesh with pinion 69 on shaft 63 when the latch arms 77 are closed. Carried on drive lever 111 is a drive pawl 121 urged into engagement with ratchet 117 by a spring 123. A bracket 125 affixed to the frame 27 pivotally carries a holding pawl 127 urged against the ratchet 117 by a spring 129. From the foregoing it can be seen that with each rightward movement of link 1139, pawl 121 will advance the ratchet 117 which, through gear 119, pinion 69, gears 65 and 37 and shaft 33 will drive feed drum 35 at a higher rate of perhaps four-to-one or five-to-one. The force available at link 109 is quite high, and the inertia of fee drum 35 and associated mechanism is rather modest, so that the brake 55 can be adjusted tightly enough to prevent any measurable overthrow of the drum by the action of its drive. On the return stroke of the link 1119, pawl 127 prevents any inadvertent reversal of the feed drum 35 which might result from the friction of driving pawl 121 on ratchet 117, or any other cause.

Means are provided for controlling the length of ribbon fed at each stroke, including a lift pin 131 projecting from the drive pawl 121. A shroud plate 133 is rockable on hub 115 and includes a cam sector 135 whose radius is large enough to hold pawl 121 out of contact with ratchet 117 wherever it intercepts the pin 131 during its oscillation. In the form shown, the teeth of ratchet 117 each represent about five degrees of rotation, and a full stroke of iink res will move the pawl nine teeth or about 45. The shroud plate 133 can be set, however, so that the drive pawl 121 fails to engage some of the teeth during the first portion of its travel in a driving direction, and therefore drives the feed drum 35 through a shorter stroke. In the position in which the shroud plate 133 is shown in FIG. 6, the pawl 121 will engage the ratchet soon enough to drive the same through about 30". In order to position the shroud plate in definite locations related to the stopping position of the ratchet teeth, the bracket 125 carries a spring detent 137 engageable with a toothed sector 139 on the shroud plate, each tooth of which corresponds to a desired setting of the shorud plate. If desired, the detent 137 may have a slight sliding motion on the bracket 125 and may have a micrometer adjustment by means of screw 138 in order to position it precisely with relation to the stopping position of the teeth on ratchet 117. The range of settings is indicated by dotted line positions C and D. In the former a single tooth or 5 travel of the ratchet 117 is effected, and in the latter nine teeth or a 45 travel of the ratchet 117 is effected at each stroke. It will be appreciated, of course, that the fineness of the adjustment may be altered by using ratchet teeth of different sizes, plural serially engaging pawls, and the like, if desired. In order to manually control the adjustment of the feed stroke, the shorud plate is attached to a control rod 141 which leads to a manual control button 143 at an accessible point on the machine. A scale 145 and index 147 may also be provided to indicate to the operator the value of the setting in terms of inches of ribbon fed.

The supply coil of ribbon is carried by the spool 17 whose spindle 153 is rotatably mounted on the bracket 19. The ribbon coil is normally Wound with its carbon layer inside and the ribbon proceeding therefrom is led from the coil bottom first over a guide roll 155 also afiixed to the bracket 19, thence via a let-off and ribbon pulling device 157 to a guide roll 1S9 affixed to frame 11, across the upper surface of anvil 13 and a printing device P positioned thereon, across the guide pin 57, and thence into the nip formed by the feed drum 35 and pressure roller 64 of the ribbon advancing mechanism 21.

A brake is applied to the spool 17 to prevent excessive spinning after a length of ribbon is withdrawn therefrom. As shown in FIG. 1 this brake comprises an arm 161 pivoted to the bracket 19 at one end with its free end carrying a bar 163 which rests rubbingly against the surface of the coil of ribbon on spool 17. A tension spring 165 urges the arm towards the spool, and the spring is made relatively iong so that only moderate change in force will be experienced as a result of the change in diameter of the coil of ribbon on the spool. The braking forces are applied to the spool by the bar 163 at exactly the same radius as the unwinding force of ribbon R is applied, so that no adjustment is required as a result of the varying unwinding torque arm. The gradual reduction of brake pressure due to reduction in size of the ribbon coil and consequent contraction of spring 165 serves to reduce the braking pressure at a slow rate. There is, of course, a reduction in mass and inertia of the spool as the ribbon is paid out, and this braking force thus tends to accommodate itself very closely to the needs of the spinning effect which the intermittent ribbon removal may tend to bring about, and exhibits a parallel gradual reduction. It has been found that a braking force of about two to two and one-half pounds at the bar 163 in a full roll situation and about one and one-half to two pounds at minimum coil diameter will operate satisfactorily. These values produce a situation wherein a ribbon pull of about 8 to 10 pounds is required to overcome the brake and start the spool turning.

In order to minimize the spinning efiect of the jerky ribbon motion which the intermittent feed engenders, the let-off 157 includes a lightweight lever preferably of aluminum pivoted on the bracket 19 at 167 and provided with an exceedingly light roller 171, preferably a thin aluminum shell, under which the ribbon R is trained. The other end of the lever is connected with a tension spring 173 which tends to urge the roller 171 'to lowered position, and which is of sufiicient length to exert fairly constant tension over its range of action. The action of the let-off 157 is to tend to maintain at least a certain amount of unwound length or slack in the ribbon which can be let-off to the feed, while the spool 17 is getting under way, to draw an additional length from the spool in preparation for another feed, and to absorb any slack which the spool may generate due to its spinning action after the feed motion stops. Because of the vector effects of the forces involved, the spring 173 will normally have ample force to draw the ribbon at least to the position shown in FIG. 1 after a feed stroke is completed, thereby providing an adequate reserve of ribbon for the next feed stroke to occur fully without any necessity for directly rotating the spool 17. The spring force is also such that it will not extend the ribbon at great deal farther than the position shown under relatively static test conditions. The spool is thereby permitted to accelerate gradually while the primary resistance to the feeding action is provided by low inertia elements consisting of lever 167 and spring 173. When the feed stroke is completed the spool 17 may tend to spin slightly and somewhat randomly. This tendency is countered by the action of device 157 which moves in a direction to bring taut any loop thus generated. The motion in this part of the mechanism is not particularly consistent, and the spool 17 may sometimes throw a loop large enough for two feed motions before it rotates again. The loop may even extend to a point below the lowermost position of roller 171 in some instances without seriously affecting the operation since the roller 167 smoothly picks up the loop on the next feed stroke due to the low inertia of the let-off system 157. Accordingly, the lever 167 may come to rest in quite a variety of angular positions, except that the highest position, after feeding has been completed and the spool 17 is not rotating, will not be significantly above that shown in FIG. 1.

After the ribbon R leaves the ribbon advancing mechanism 21, it is guided over fixed axis rollers 175 and 177, and thence via a take-up and spool arresting device 179 to the collecting spool 23. The mounting of the spool is illustrated in detail in FIG. 5 which shows a bearing 181 aflixed to the bracket and rotatably supporting a spindle 183. To the front end of the spindle for rotation therewith is secured the spool 23. Behind the bearing 181 the spindle rotatably carries a drive sleeve 185 which includes a pulley 187 continuously rotated from the main drive of the printing machine by a belt 189. The sleeve 185 and spindle 183 are connected by an adjustable friction slip clutch 191 whose maximum torque before slippage can be set by means of an adjusting nut 193 threaded on sleeve 185. The spool 23 tends to be turned in a winding direction, whenever the machine is running, by the rotation of pulley 187 acting through the slip clutch 191. Whenever the ribbon R is not being fed to the spool the maximum torque transmission of clutch 191 is overcome and the pulley 187 continues to rotate with the clutch slipping. Accordingly, a substantially constant torque is continuously being applied to spool 23 in a Winding direction, and the adjustment is such as to permit a setting which will allow the clutch to slip at a ribbon tension in the range of about three to six pounds.

Between the spool 23 and guide 177 is the take-up device 179 comprising an aluminum lever 195 pivoted on the bracket 25 at one end and carrying at its free end a guide roller 197 consisting of a thin shell of aluminum over which the ribbon R is trained. A tension spring 199 urges the arm 195 upwardly to lightly tension the ribbon. Whenever a feed stroke occurs at 21 the spool 23 starts to rotate, but its inertia is such that it cannot keep up with the motion, and slack tends to form in the ribbon R between the advancing mechanism 21 and spool 23. The inertia of the take-up system 179 is low, however, so that the roller 197 can follow the ribbon and keep it taut until the collection spool drive has time to cause the spool 23 to rotate sufficiently to collect the amount of ribbon fed forward and return the take-up device 179 to its original location. The take-up device is, in effect, balanced against the torque of the clutch 191, and the clutch 191 is so adjusted as to apply suflicient torque to cause the lever 195 to oscillate generally between the radial positions indicated by bracket A when the ribbon has been freshly changed. When the ribbon is partially wound, as indicated in the drawing, the lever 195 will stand approximately in the full line position when static equilibrium is reached, and attain perhaps the dotted line position at the peak of the feed stroke, covering a range indicated by bracket B. Bracket C indicates the range of travel of the lever 195 as the end of the ribbon is approached. It can be seen that the constant torque of clutch 191 acts against the tension of the ribbon R acting at an increasing radius arm. This provides a continually increasing mechanical advantage for the ribbon tension, hence the gradual shift in the range over which the lever 195 oscillates during an individual feed cycle. The system disposes itself in a geometrical arrangement such that the ribbon tension, generated as a result of the pull of spring 199, keeps decreasing and therefore maintains a torque just sufficient to balance that exerted by the clutch 191 and bring the collection spool 23 to a halt when it has wound the amount of ribbon fed forward. In any condition, the pull of spring 199 will be sufiicient to stop rotation of spool 23 before the ribbon moves the arm 195 to its low limit, and weak enough to prevent arm 195 from moving to its upward limiting position.

In operation the device may be set up for use by placing a coil of ribbon R on the supply spool 17, carrying the leading end of the ribbon over guide 155 under roller 171 over guide 159, and across the anvil 13 and guide pin 57. Screws 95 are loosened and the clamp plate-scraper assembly 91, 97 is removed. Latch arms 77 are raised to allow pressure roller 64 to move away from the feed drum and a length of the ribbon is passed between them. The latch arms 77 are then lowered to bring the pressure roller 64 into engagement with the ribbon and force it against the feed drum 35. The clamp plate-scraper assembly 91, 97 is replaced and the screws 95 tightened down. The free end of the ribbon is then led around guides 175 and 177, over the roller 197 and fiinally attached to spool 23. In case additional ribbon is needed during this process, it may be readily fed forward by placing the crank 105 in socket 103 and turning the feed drum 35 via gears 65 and 37.

When the threading of the ribbon is completed, the operator will then, by means of knob 143, set the shroud plate 133 to give the length of feed stroke required for the assignment at hand.

The machine is next turned on and proceeds to go through a series of printing cycles. While the platen 15 is taking an impression from printing device P, link 109 is moving towards the left and the ribbon R is stationary. When the printing operation stops, link 109 moves towards the right thereby driving the feed drum through pawl 121, ratchet 117, gear 119, pinion 69, shaft 63, gear 65 and gear 37 whatever amount is permitted as determined by the setting of shroud plate 133. In spite of the rapid and somewhat jerky motion of the drive mechanism when the machine is operated at high speed, the feed drum moves an accurately determined amount and stops precisely at the end of the feed stroke due to the action of brake 55. Moreover the supply and collection spools 17 and 23 move in a smooth, rather evenly paced manner under the influence of the brake 151, 163 and the let-off 157 on the one hand, and drive 187, clutch 191 and takeup 179 on the other.

From the foregoing description it can be seen that the present invention provides a ribbon feeding arrangement capable of handling and stepping forward with a rapid long-stroke intermittent movement a strip of delicate material even though the latter is carried on a large supply spool of relatively great mass, and capable of doing so in an accurate manner and without danger of breaking the strip. Moreover these advantages are secured with a mechanism which is mechanically relatively simple and capable of notably economical construction.

While the forms of the invention shown and described herein are admirably adapted to fulfill the objects primarily stated, it is to be understood that it is not intended to confine the invention to the forms disclosed herein, for the invention is susceptible of embodiment in other forms and variations. It will be understood, therefore, that the invention is claimed in any of its forms or modifications falling within the spirit and scope of the language employed in the appended claims.

I claim:

1. A ribbon feed mechanism for intermittently moving a delicate ribbon from a heavy rotary supply past a point of use to a collection point in accurately measured steps of substantial length comprising: a rotary feed drum arranged for contact with the ribbon; means for pressing the ribbon firmly against the surface of the feed drum for positive driving thereby; means for alternately driving the feed drum through a predetermined feed angle and holding it immobile for a working period; a supply spool for carrying a coil of ribbon with a reach thereof extending between said spool and said feed drum; a friction brake acting rubbingly on the periphery of a ribbon coil on said supply spool; a low inertia let-otf device acting against the ribbon between said spool and said drum; and spring means urging said let-off device in a direction to deflect the ribbon transversely of its normal taut path between said spool and said drum, the urging effect of said urging means being of sufficient magnitude to insure that, working indepentently in opposition to said friction brake, a degree of ribbon deflection representing the lengthening of the ribbon reach by an amount at least equal to the amount of ribbon fed by a feeding operation of said feed drum is achieved.

2. A ribbon feed mechanism for intermittently moving a delicate ribbon from a heavy rotary supply past a point of use to a collection point in accurately measured steps of substantial length comprising: a rotary feed drum arranged for contact with the ribbon; means for pressing the ribbon firmly against the surface of the feed drum for positive driving thereby; means for alternately driving the feed drum through a predetermined feed angle and holding it immobile for a working period; a supply spool for carrying a coil of ribbon with a reach thereof extending between said spool and said feed drum; a friction brake acting rubbingly on the periphery of a ribbon coil on said sup-ply spool; a low inertia let-off device acting against t-he ribbon between said spool and said drum; spring means urging said let-ofi device in a direction to deflect the ribbon transversely of its normal taut path between said spool and said drum, the urging effect of said urging means being of sufficient magnitude to insure that, working independently in opposition to said friction brake a degree of ribbon deflection representing the lengthening of the ribbon reach by an amount at least equal to the amount of ribbon fed by a feeding operation of said feed drum is achieved; a collection spool for gathering the ribbon and arranged to accept ribbon trained in a collection reach extending thereto from said feed drum; rotary means continually urging said collecting spool in a direction of rotation tending to wind the ribbon thereon; a low inertia take-up device acting against the ribbon between said collecting spool and said drum; and means urging said take-up device in a direction to deflect the ribbon transversely of its normal taut path between said feed drum and said collection spool, the urging effect of said take-up urging means being of suificieut magnitude to overcome the rotary urging means and arrest the motion of the collection spool prior to exhausting the transverse deflection of said ribbon generated by said take-up.

3. A ribbon feed mechanism for intermittently feeding a delicate ribbon from a heavy rotary supply past a point of use to a collection point in accurately measured steps of substantial length comprising: a rotary feed drum arranged for contact with the ribbon; means for pressing the ribbon firmly against the surface of the feed drum for positive driving thereby; a reciprocating drive means movable in alternate directions through a predetermined distance, means associated with said drum and said drive means for actuation of the former in a feed direction by the latter in one direction of drive means motion and for releasing the drum from connection with the drive means in the other; means for adjusting the degree of feeding movement of said drum resulting from each stroke of the drive means; an adjustable friction brake connected to said drum for preventing further travel of said drum in the feed direction when released; a supply spool for carrying a coil of ribbon with a reach thereof extending between said spool and said feed drum; a friction brake acting rubbingly on the periphery of a ribbon coil on said supply spool; a low inertia let-off device acting against the ribbon between said spool and said drum; and spring means urging said let-off device in a direction to deflect the ribbon transversely of its normal taut path between said spool and said drum, the urging effect of said urging means being of suflicient magnitude to insure that, working independently in opposition to said supply spool brake, a degree of ribbon deflection representing the lengthening of the ribbon reach by an amount at least equal to the amount of ribbon fed by a complete feed stroke of said feed drum is achieved.

4. A ribbon feed mechanism for intermittently moving a delicate ribbon from a heavy rotary supply past a point of use to a collection point in accurately measured steps of substantial length comprising: a rotary feed drum arranged for contact with the ribbon; means for pressing the ribbon firmly against the surface of the feed drum for positive driving thereby including a roller mounted adjacent said feed drum, spring means clear of the ribbon path for separating said roller from said feed drum, and latch means for holding said roller in pressure contact with said feed drum in opposition to said spring means; means for alternately driving the feed drum through a predetermined feed angle and holding it immobile for a printing period; a supply spool for carrying a coil of ribbon with a reach thereof extending between said spool and said feed drum; a friction brake acting on the periphery of a ribbon coil on said supply spool; a low inertia let-off device acting against the ribbon between said spool and said drum; and means urging said let-off device in a direction to deflect the ribbon transversely of its normal taut path between said spool and said drum, the urging effect of said urging means being of sufficient magnitude to insure independently a degree of ribbon deflection representing the lengthening of the ribbon reach by an amount at least equal to the amount of ribbon fed by a feeding operation of said feed drum.

5. A ribbon feed mechanism for intermittently moving a delicate carbon paper rib-bon from a heavy rotary supply past a point of use to a collection point in accurately measured steps of substantial length comprising: a rotary feed drum arranged for contact with the carbonfree surface of the ribbon; a pressure roller adjacent the feed drum and located at one side thereof; means for pressing the roller against the carbon carrying surface of the ribbon and holding it against the feed drum, and including a releasable element for permitting separation of said roller from said drum for ribbon threading, a scraper carried by said releasable element in a position to approach a surface of said roller for loosening any carbon material accumulated thereon, said scraper being so positioned relative to said pressure roller as to provide for gravity discharge of the loosened carbon material away from said drum and roller and being removable together with said releasable element to clear the path for separation of said roller; means for alternately driving the feed drum through a predetermined feed angle and holding it immobile for a printing period; a supply spool for carrying a coil of ribbon with a reach thereof extending between said spool and said feed drum; a friction brake acting on the periphery of a ribbon coil on said supply spool; a low inertia let-off device acting against the ribbon between said spool and said drum; and means urging said let-off device in a direction to deflect the ribbon transversely of its normal taut path between said spool and said drum, the urging effect of said urging means being of sufficient magnitude to insure independently a degree of ribbon deflection representing the lengthening of the ribbon reach by an amount at least equal to the amount of ribbon fed by a feeding operation of said feed drum.

6. A ribbon feed mechanism as set forth in claim 5 in which said feed drum has a hard, roughened surface, and in which said pressure roller is smooth surfaced and at least somewhat resilient.

7. A ribbon mechanism comprising: a roughened, hardsunfaced feed drum; means for driving the drum; a smooth resilient pressure roller adjacent thereto; a shaft supporting said pressure roller; means clear of the ribbon path urging said shaft away from said drum to separate the drum and roller; latch means having an operative position holding the shaft towards said drum and thereby holding the drum and roller in ribbon feeding relation and an inoperative position releasing the shaft to allow the roller to separate from the drum under the influence of said urging means; means for retaining said latch means in operative position; means for intermittently driving said drum; and brake means associated with said drum for preventing over-run thereof at the end of each driving operation.

8. A ribbon feed mechanism as set forth in claim 7 in which the latch means comprises a pair of pivoted arms, each associated with one end of the pressure roller shaft, and an eccentrically mounted pivot for each of said arms for accurately adjusting the alignment of said roller with said drum and the degree of pressure therebetween.

9. A ribbon feed mechanism as set forth in claim 7 which further includes a scraper positioned for cooperation with the pressure roller at the side away from the feed drum, and in which the scraper coacts with the retaining means for the latch means for automatic separation thereof from the roller when the retaining means is released to permit separation of the roller and drum.

10. A ribbon feed mechanism as set forth in claim 7 in which the pressure roller is free on the shaft and in which the means for driving the drum includes a gear drivingly attached to the drum, a meshing gear drivingly attached to the roller shaft, and a pinion also drivingly attached to the roller shaft.

11. A ribbon feed mechanism for feeding a carbon paper ribbon comprising: a roughened, hard-surfaced rotary feed drum arranged for contact with the carbon- References Cited by the Examiner UNITED STATES PATENTS 1,400,827 12/1921 Leumann 226-114 X 1,497,766 6/1924 Balkwill 101-247X 1,781,395 1171930 Johnson 101 336 1? Cava gnaro 2261 14 Paulsen 226144 X Hahn 101336 Rouan 27156 Kamp 197--151 Freedson 1976.6

Whitehurst 15-25651 Rosenblum 2271 14 X Anderson et a1. 2261 14 X 10 ROBERT B. REEVES, Primary Examiner.

ROBERT E. PULFREY, Examiner. 

1. A RIBBON FEED MECHANISM FOR INTERMITTENTLY MOVING A DELICATE RIBBON FROM A HEAVY ROTARY SUPPLY PAST A POINT OF USE TO A COLLECTION POINT IN ACCURATELY MEASURED STEPS OF SUBSTANTIAL LENGTH COMPRISING: A ROTARY FEED DRUM ARRANGED FOR CONTACT WITH THE RIBBON; MEANS FOR PRESSING THE RIBBON FIRMLY AGAINST THE SURFACE OF THE FEED DRUM FOR POSITIVE DRIVING THEREBY; MEANS FOR ALTERNATELY DRIVING THE FEED DRUM THROUGH A PREDETERMINED FEED ANGLE AND HOLDING IT IMMOBILE FOR A WORKING PERIOD; A SUPPLY SPOOL FOR CARRYING A COIL OF RIBBON WITH A REACH THEREOF EXTENDING BETWEEN SAID SPOOL AND SAID FEED DRUM; A FRICTION BRAKE ACTING RUBBINGLY ON THE PERIPHERY OF A RIBBON COIL ON SAID SUPPLY SPOOL; A LOW INERTIA LET-OFF DEVICE ACTING AGAINST THE RIBBON BETWEEN SAID SPOOL AND SAID DRUM; AND SPRING MEANS URGING SAID LET-OFF DEVICE IN A DIRECTION TO DEFLECT THE RIBBON TRANSVERSELY OF ITS NORMAL TAUT PATH BETWEEN SAID SPOOL AND SAID DRUM, THE URGING EFFECT OF SAID URGING MEANS BEING OF SUFFICIENT MAGNITUDE TO INSURE THAT, WORKING INDEPENTENTLY IN OPPOSITION TO SAID FRICTION BRAKE, A DEGREE OF RIBBON DEFLECTION REPRESENTING THE LENGTHENING OF THE RIBBON REACH BY AN AMOUNT AT LEAST EQUAL TO THE AMOUNT OF RIBBON FED BY A FEEDING OPERATION OF SAID FEED DRUM IS ACHIEVED. 